Question about lips over steam water

When is the time I should do this? At the end of the cycle when they are about to peel? Or when they have just peeled? If its when they are about to peel do I just hold my head over the steam with a towel over my head? Will the skin just fall off or is there somthing to it? If somone could help me with this it would be much appreciated. Thanks to all in advance (: